Transcriptomic and proteomic responses to very low CO2 suggest multiple carbon concentrating mechanisms in Nannochloropsis oceanica
Transcriptomic and proteomic responses to very low CO2 suggest multiple carbon concentrating mechanisms in Nannochloropsis oceanica
复制标题
对极低二氧化碳的转录组和蛋白质组反应表明微拟球藻存在多种碳浓缩机制
DOI：
10.1186/s13068-019-1506-8
复制
发表时间：
2019-06-28
影响因子：
6.3
通讯作者：
Xu, Jian
中科院分区：
文献类型：
--
作者：
Wei, Li;El Hajjami, Mohamed;Xu, Jian
背景在微拟球藻等工业产油微藻中，碳浓缩机制 (CCM) 机制的关键组成部分尚不清楚，并且如何动员它们促进细胞利用无机碳仍然难以捉摸。结果对于海洋微拟球藻，为了解开由 CO2 消耗特异性诱导的基因，从而潜在地支撑其 CCM，转录组、蛋白质组和代谢组谱在 0 小时内进行了跟踪，细胞从高 CO2 水平（HC；50,000ppm）到极低 CO2（VLC；100ppm）反应期间的 3 小时、6 小时、12 小时和 24 小时。生物物理 CCM 的活性是基于在 VLC 下诱导编码碳酸氢盐转运蛋白和两种碳酸酐酶的转录本来证明的。此外，VLC 下许多关键 C4 样途径酶在蛋白质丰度和酶活性上的上调支持了潜在生化 CCM 的存在，这与线粒体相关的基于 C4 的 CCM 一致。此外，可能存在由 VLC 诱导的光呼吸上调和鸟氨酸-瓜氨酸穿梭和鸟氨酸尿素循环下调所支持的基础 CCM，这可能负责叶绿体碳固定中线粒体 CO2 的有效循环。结论 大洋微绿球藻似乎动员了一整套 CCM 来响应极低的 CO2。它由应激诱导的基因与莱茵衣藻和三角褐指藻的基因非常不同，这表明 CCM 受到严格调控但相当独特。这些发现可以为合理设计 CCM 以增强工业微藻的碳固定和生物质生产力迈出第一步。
BackgroundIn industrial oleaginous microalgae such as Nannochloropsis spp., the key components of the carbon concentration mechanism (CCM) machineries are poorly defined, and how they are mobilized to facilitate cellular utilization of inorganic carbon remains elusive.ResultsFor Nannochloropsis oceanica, to unravel genes specifically induced by CO2 depletion which are thus potentially underpinning its CCMs, transcriptome, proteome and metabolome profiles were tracked over 0h, 3h, 6h, 12h and 24h during cellular response from high CO2 level (HC; 50,000ppm) to very low CO2 (VLC; 100ppm). The activity of a biophysical CCM is evidenced based on induction of transcripts encoding a bicarbonate transporter and two carbonic anhydrases under VLC. Moreover, the presence of a potential biochemical CCM is supported by the upregulation of a number of key C4-like pathway enzymes in both protein abundance and enzymatic activity under VLC, consistent with a mitochondria-implicated C4-based CCM. Furthermore, a basal CCM underpinned by VLC-induced upregulation of photorespiration and downregulation of ornithine-citrulline shuttle and the ornithine urea cycles is likely present, which may be responsible for efficient recycling of mitochondrial CO2 for chloroplastic carbon fixation.ConclusionsNannochloropsis oceanica appears to mobilize a comprehensive set of CCMs in response to very low CO2. Its genes induced by the stress are quite distinct from those of Chlamydomonas reinhardtiiandPhaeodactylum tricornutum, suggesting tightly regulated yet rather unique CCMs. These findings can serve the first step toward rational engineering of the CCMs for enhanced carbon fixation and biomass productivity in industrial microalgae.